1. Field of the Invention
The present invention relates generally to medical apparatus and methods. More particularly, the present invention relates to methods and systems for intraluminal vein harvesting or removal.
Cardiac and peripheral vascular bypass surgery commonly employs veins harvested from the patient undergoing surgery, usually obtained by autologous vein harvesting procedures. Vein harvesting commonly relies on making a long skin incision to expose the length of vein which is to be excised and removed. Such exposure of the vein allows for dissection and division of the veins which branch from the portion of vein being removed. The greater saphenous vein in the leg is most commonly used, followed by the lesser saphenous vein in the leg and the basilic and cephalic veins in the arm.
Such long incisions made for vein harvesting are highly traumatic and problematic for a number of reasons. First, patients requiring bypass surgery often suffer from other diseases, such as diabetes, obesity, malnutrition, which may impede healing and increase the risk of infection of the skin incisions. Additionally, the cosmetic scarring which results from the long incisions is of concern to many patients.
To partly overcome these drawbacks, systems for the endoscopic harvesting of veins have been developed. Such systems, presently available from suppliers such as Ethicon and General Surgical Innovations, rely on introduction of endoscopic apparatus through an incision at one end of the vein segment to be removed. The apparatus includes a viewing scope, a mechanism for dissecting the vein from the surrounding tissue bed, and additional mechanisms for dissecting the vein from side branches to facilitate removal. Other systems, such as that available from Guidant Corporation, use gas insufflation to create a working space around the vein and rely on percutaneously introduced instruments for excising the vein. In all cases, the systems are expensive, cumbersome to use, and still traumatic to the patient.
For these reasons, it would be desirable to provide improved vein harvesting apparatus and methods for their use, which are minimally traumatic to the patient, which do not require long skin penetrations or incisions at points between the two ends of the vein segment being removed, which permit selective excision of the venous side branches and optional sealing of the side branches, and which provide a vein segment which is maintained relatively intact allows for valve removal and which can be used for bypass grafting or other purposes with minimal additional preparation. It would be further desirable if the systems and methods were also useful for vein stripping and removal for treatment of varicose veins and other conditions. The system and methods should optionally permit endoscopic visualization of the vein while it is being removed and remove relatively long vein segments with a single device deployment. At least some of these objectives will be met by the inventions described hereinafter.
2. Description of the Background Art
Intraluminal vein removal and modification devices are described in U.S. Pat. Nos. 6,165,172; 6,030,396; 6,013,073; 5,843,104; 4,528,982; 3,788,325; 3,568,677; 3,185,155; 3,045,676; 2,770,334; and PCT Publication WO 00/45691. Endoscopic and extraluminal vein removal devices are described in U.S. Pat. Nos. 6,022,313; 5,817,013; 4,793,346; and Re. 36,053. Patents relating to vein harvesting assigned to General Surgical Innovations include U.S. Pat. Nos. 6,196,968; 6,077,289; 6,068,639; 5,993,412; 5,968,066; 5,944,734; 5,899,913; and 5,853,417. Patents relating to vein harvesting assigned to Ethicon include U.S. Pat. Nos. 6,193,653; 5,928,138; 5,922,004; 5,902,315; and 5,667,480.
The present invention provides improved methods, systems, and kits for removing veins from their surrounding tissue beds. While the methods will find their greatest use in the harvesting of veins for subsequent implantation in bypass and other procedures, they will also find use for removing varicose veins and diseased veins for cosmetic and other purposes. When used for vein harvesting, the target veins will most often be the greater saphenous vein or the lesser saphenous vein in the leg, and the basilic and cephalic veins in the arm.
The present invention is advantageous in a number of respects. It does not require a long incision along the length of the vein segment to be removed. Instead, it is less invasive and may be performed via surgical cut downs at each end of the vein segment to be removed. Additionally, the present invention allows for selective severing of venous side branches from the vein segment being removed during the removal process. In one embodiment of the present invention, such selective severing (and optionally subsequent sealing) of the side branches may be performed under direct endoscopic visualization. In another embodiment, such selective severing is achieved in a blind fashion, greatly simplifying the protocols. Use of the methods and apparatus of the present invention has been found to produce very long and high quality vein segments suitable for coronary artery and other bypass and implantation procedures. In some embodiments, the apparatus of the present invention facilitates manipulation of the long vein segments after they have been removed, in particular allowing trimming of the valves and other preparation steps to be performed while the vein remains over a long distal portion of the vein removal catheter.
In a first aspect, methods according to the present invention for vein removal comprise exposing first and second spaced-apart locations along a vein, typically by surgically exposing the locations, commonly referred to as a surgical cut down. The veins are then transected at each of the locations so that a segment of the vein is isolated and ready for removal from the surrounding tissue bed. The remaining portions of the vein, i.e., those which are not to be removed, may have their free ends tied off or otherwise sealed.
After exposing and transecting the ends of the venous segment to be removed, a guidewire is passed through a lumen between the first and second locations. The length of the guidewire is sufficient to permit introduction of intraluminal devices over at least one end, and preferably over both ends, of the guidewire to perform the methods described herein. In particular, a pull catheter will be introduced over the guidewire from the first location until a distal end of the pull catheter reaches the second location. Usually, the first location will be that which is closest to the patient""s heart and which therefore has a larger diameter.
Alternatively, the pull catheter may have a fixed rail at its distal end or the pull catheter may be provided with a rail immobilization mechanism for selectively holding a movable rail with the distal end of the movable rail exposed distally out the pull catheter. In either case, the pull catheter may be introduced to and through the target vein without the prior positioning of a movable rail. With a fixed rail, the rail would be designed to be long enough to allow introduction of a side branch management catheter (as described below) excision or other catheter over a movable rail in a direction opposite to that of the pull catheter. An advantage of using a pull catheter and a fixed rail is that there is no need to separately manipulate a long guidewire, which when both a pull catheter and an side branch management tool are to be introduced, may have a length which is more than three times that of the individual catheters. A similar advantage is found with the use of the immobilized rail, where the rail could have a length only slightly longer than that of the pull catheter. The immobilized guidewire, however, could be released after the pull catheter is extended distally so that it could remain in place as the pull catheter is withdrawn from the vessel. An advantage of both these alternative rail designs, is that introduction of a side branch management or other catheter from the remote tissue penetration, as described below, will be more easier. In addition, the fixed rail embodiment provides support for the inverted vein after removal and can help in re-inverting the vein and other vein preparation steps.
After the pull catheter has been introduced to the desired location, the free end of the vein which has been transected near the second location is attached to the distal catheter end, typically by suturing, clipping, tying, or otherwise circumferentially securing the venous end to the distal end of the pull catheter. The pull catheter is then pulled in a direction back from the second location toward the first location so that the end of the xe2x80x9cfreexe2x80x9d venous segment to be removed is inverted. In particular, the free end is pulled inwardly and to the lumen of the venous segment with a continually retracting inversion fold line being exposed as the vein is pulled from the surrounding tissue bed.
As the venous segment is inverted and pulled from the surrounding tissue bed, the venous wall will be pulled from the side branches which extend radially outwardly into the surrounding tissue bed. In some instances, the wall of the venous segment can simply be pulled or evulsed from the attached end of the side branch. For larger side branches, however, it may be desirable to divide and optionally occlude the side branches from the wall of the venous segment prior to removal of the vein. According to the present invention, this can be accomplished by introducing a side branch management tool, preferably over the guidewire, through the second location and advancing a distal end of the side branch management tool so that it follows an inversion line of the venous segment as it is being inverted. The side branch management tool will usually include at least a cutting tool and may optionally include a sealing tool and/or viewing optics. The cutting tool can be a deployable or fixed blade, an electrosurgical cutting tool, a shearing blade, or the like. The occlusion device could be an electrocautery device, a clip applier, a hemostatic or glue applicator, or the like. The optional optical viewing system will normally comprise an optical fiber system, but could comprise a CCD or other electronic monitor directly on the tool.
Severing of the side branches can be achieved in a number of ways, including both blind and under visualization. Removal of the side branches under visualization can be accomplished, for example, using a catheter having a viewing scope positioned in or alongside the side branch management tool to visualize the inversion folding edge, referred to herein as the inversion line, as the venous segment is inverted. When side branches which need to be severed are observed, a separate or integral cutting blade or other tool can be advanced from the side branch management tool and used to selectively cut the side branch near its attachment point to the venous segment. Blind side branch management tools may comprise simple tubular cutting blades or tubular cutting blades having castellated or serpentine cutting edges. Alternatively, blind tools may comprise a blunt or acorn tip which may be advanced so that it embeds into the inverted venous wall as it is being pulled. Fixed or actuable blade(s) on the tool may then be used to cut the side branches when the user determines that a side branch is impeding the vein removal. Usually, the catheter tip will be rotated so that the blade circumscribes a line positioned just behind the inversion line, thus selectively isolating, tensioning and severing the side branches which are attached at that point. A variety of other cutting mechanisms and protocols could also be used, such as a gripping or clamping tool that pulls vessel out by it""s root.
A particular advantage of the present invention is that the visualization and optional cutting of the side branches is accomplished using a side branch management tool introduced in a direction opposite to that of the pull catheter. In contrast to the endoscopic devices of the prior art which combine vessel dissection and side branch excision functions, the separate pull catheter and side branch management tool of the present invention can have relatively low profiles greatly reducing the trauma to the patient which results from advancing the catheters subcutaneously through the tissue bed. Moreover, as the vein is inverted, the side branch management tool can utilize the space left by the removed vein in the tissue bed so that additional dissection is minimized.
Optionally, after the side branches are cut, the side branch management tool can be used to seal portions of the side branch which remains in the tissue bed. For example, the cutting blade which is used to sever the side branches may be connected to an electrocautery power supply (RF or DC current) in order to cauterize the side branches. Alternatively, the side branches could be clipped or stapled, or as a third alternative, the side branches could be sealed using a tissue sealant, such as polyacrylate or a thrombin-based hemostatic agent.
In a second aspect of the present invention, systems for the removal of veins, either for harvesting or varicose vein removal, comprise a pull catheter, a side branch management tool, and usually a separate (immovable) guidewire. The guidewire will be capable of extending from a proximal location to a spaced-apart distal location along a vein. The guidewire will typically have a length in the range from 180 cm to 260 cm and a diameter in the range from 0.2 mm to 0.9 mm (usually 0.035xe2x80x3).
The pull catheter will comprise a catheter body having at least one lumen therethrough adapted to permit introduction over the guidewire. Typically, the pull catheter will have an over-the-wire design where the guidewire lumen extends the entire length of the catheter body. Alternatively, the pull catheter could have a shortened guidewire lumen extending over only a portion of the distal end, typically from 5 cm to 25 cm, usually from 5 cm to 15 cm. As a still further alternative, the pull catheter could have a fixed rail at its distal end, typically having a length in the range from 80 cm to 100 cm, usually from 80 cm to 100 cm. When used with movable guidewires, the pull catheter can optionally have a mechanism for capturing the guidewire, such as a clamp, so that a distal portion of the movable guidewire can be extended distally of the distal end of the pull catheter and then immobilized in place. In this way, the pull catheter can be initially introduced through the lumen of the target lumen in a manner analogous to the use of a catheter having a fixed guidewire. After advancing the pull catheter to the remote end of the target lumen, the guidewire can be grasped by the user and released from the catheter so that the catheter may be freely advanced and retracted over the now-movable guidewire. The pull catheter can have at least a second lumen to permit the infusion of saline or other solutions, although combined guidewire and infusion lumens may also find use. As a still further option, the pull catheter may be provided with a balloon near its distal end, where the balloon can be inflated to help initiate inversion of the vein.
Provision will be made at or near the distal end of the pull catheter to permit attachment of a dissected end of the venous segment to be removed. Most simply, the surgeon could use a clip or directly suture the vein through a distal region of the pull catheter. No particular modification of the pull catheter is required. More usually, however, the pull catheter will have a transverse aperture therethrough to permit suture or other type of clipping device to be passed through the catheter and secured over the venous segment. Alternatively, a circumferential channel or trough may be formed in the catheter body to again facilitate suturing or other attachment of the venous wall to the catheter. Of course, the vein could be attached to the pull catheter using clips, staples, metal ties, C-clamps, or in a variety of other ways. In all cases, however, it will be preferable that the free end of the venous segment be attached substantially uniformly about its circumference so that force is transmitted evenly to the vein as it is pulled and inverted from the tissue bed.
The side branch management tool will also comprise a rigid body or catheter having a guidewire lumen or other means for being introduced over a guidewire. Again, the side branch management tool may have an over-the-wire design where a guidewire lumen extends the entire length of the catheter body. Alternatively, the length of the guidewire lumen can be shortened, generally to the ranges set forth above with regard to the pull catheter. The side branch management tool will typically also have some provision for dissecting or cutting the venous side branches from the venous segment which is being withdrawn.
Usually, the side branch management tool will include a fixed or retractable blade attached near a distal end of the side branch management tool. By rotating the catheter, or at least a portion thereof that has the blade, the blade will travel circumferentially around a path which can be aligned with the expected position of the side branches. Alternatively, the blade can have a generally tubular configuration so that it can cut along the entire circumferential surface of the tissue bed as it is being exposed by the venous segment being inverted. In all cases the blade can optionally be connected to an electrosurgical power supply so that the cutting may be enhanced by the application of DC or radiofrequency energy. In such cases, the power supply could also provide radiofrequency energy intended to cauterize the cut surfaces.
The side branch management tool may optionally be provided with a viewing scope to permit visualization of the side branches and to permit more careful positioning of the blade or associated cutting mechanism in order to sever the side branches. Usually, the side branch management tool will have a lumen or other channel for introducing a working tool for cutting the side branch under endoscopic visualization. Numerous blades, scissors, electrosurgical tools, and the like, could be introduced through the side branch management tool and used under endoscopic visualization to selectively cut the side branches. Alternatively, the cutting mechanism may be formed as an integral component of the catheter.
In a specific embodiment, the side branch management tool may have a distal tip that includes a feature, such as a notch or raised edge, to catch and tension a side branch prior to dissection. Such a feature allows the surgeon to feel when the tool has encountered a side branch and further allows the surgeon to then dissect the side branch by firmly engaging the feature against the side branch and rotating, translating, or otherwise manipulating the tool to dissect the side branch. If the side branch is sufficiently small (less than 2 mm in diameter) the surgeon may evulse the branch using forward traction on the side branch management tool. Usually, the tool will also be provided with a cutting blade or other cutting feature which allows the user to first capture and tension the side branch, optionally clip and then selectively actuate the cutting blade to dissect the side branch. Optionally, the side branch management tool will include visualization which permits the surgeon to view the side branch after it has been captured and to observe the side branch as it is being dissected by the cutting blade.
The sizes of both the pull catheter and the side branch management tool may vary depending on the particular venous segment which is to be withdrawn. For the greater and lesser saphenous veins and the basilic and cephalic veins, the catheter bodies will typically have a length in the range from 40 cm to 80 cm and a body diameter in the range from 4 mm to 12 mm.
Kits according to the present invention for vein removal will also comprise a guidewire, a pull catheter, and an side branch management tool. In addition to these components, which preferably will be as described above with respect to the systems, the kits will also include instructions for use, sending forth a method according to the present invention for vein removal. The methods may be any of the methods described herein above. Typically, the kits will further include packaging for holding the guidewire, pull catheter, and side branch management tool, preferably all in a sterile condition. Suitable packages include pouches, tubes, boxes, trays, and the like. The instructions for use will typically be printed on a sheet of paper, usually in the form of a product insert. Alternatively, the instructions for use may be printed directly on the packaging. In other cases, the instructions for use may be made available electronically, e.g., on CD-ROMs, sold as a part of the kit, or made available over the Internet. In all cases, the instructions for use will inform the user on how to use the physical components of the kit to perform the methods in an acceptable manner.